Heat exchanger with corrosion protection

Abstract

Heat exchanger with corrosion protection. The present invention relates to a heat exchanger (2) comprising a plate bundle (4) and at least one flange (6) bordering the plate bundle (4), the material of the plates and the flange (6) comprising at least aluminum, the heat exchanger (2) being characterized in that it further comprises at least one additional plate (14, 16) attached to the flange (6) or to the plate bundle (4) and forming an electrical contact with the flange (6) or the plate bundle (4), the additional plate (14, 16) comprising zinc in a proportion of between 0.5 and 1.8% of the mass of the additional plate (14, 16). (Figure 1)

Description

Title of the invention: Heat exchanger having protection against corrosion

[0001] The present invention relates to the field of cooling circuits, and more specifically concerns a heat exchanger comprising a bundle of metal plates, in particular made of aluminum. The invention finds a particular application in the automotive field.

[0002] The heat exchangers equipping the air conditioning loops of vehicles are arranged to allow the adjacent circulation in two separate spaces of two different fluids, in particular a heat transfer fluid and a refrigerant fluid, so as to achieve a heat exchange between these fluids, without mixing them. Within the heat exchangers and the thermodynamic circuits to which they are attached, the fluids circulate under pressure.

[0003] In a plate heat exchanger, a bundle of metal plates welded or brazed together forms an alternation of channels dedicated to the circulation of a heat transfer liquid and channels dedicated to the circulation of a refrigerant fluid, the channels being served by openings arranged in the plates.

[0004] Since such a heat exchanger is metallic, it is subject to corrosion. Indeed, in a cooling circuit of a motor vehicle, it is often integrated in a corrosive environment such as the engine compartment or a location under the chassis of the vehicle.

[0005] The design of such a heat exchanger, and in particular the composition of its plates, are nevertheless such that corrosion on this type of heat exchanger does not generally affect the proper functioning of the cooling circuit during the lifetime of the vehicle. The choice of materials used to make the heat exchanger plates takes into account the resulting cost, their resistance to external corrosion and their mechanical resistance, in particular to the pressure of the fluids passing through them. However, in certain countries of the world, with a humid climate, such a heat exchanger can lead to serious corrosion problems.

[0006] However, for cost reasons, adapting the design and composition of the heat exchanger plates to all possible climates is not feasible.

[0007] The present invention at least partially overcomes the drawbacks of the prior art by providing a heat exchanger equipped with modular protection against external corrosion, making it possible to effectively slow down the rate of corrosion and increase the service life of the exchanger compared to the same exchanger without this protection, while having adequate mechanical resistance.

[0008] To this end, the invention proposes a heat exchanger comprising a bundle of plates and at least one cheek bordering the bundle of plates, the material of the plates and of the cheek comprising at least aluminum, the heat exchanger being characterized in that it further comprises at least one additional plate secured to the cheek or to the bundle of plates and forming an electrical contact with the cheek or the bundle of plates, the additional plate comprising Zinc in a proportion of between 0.5 and 1.8% of the mass of the additional plate.

[0009] The material of the plates and the cheek is preferably an aluminum of the 1000 series, the 3000 series or the 6000 series.

[0010] Thanks to the invention, a standard heat exchanger for countries whose climate is not very conducive to corrosion, is easily adapted to countries with a humid climate by brazing, welding or gluing the additional plate on the cheek or the bundle of plates of the heat exchanger according to the invention, this additional plate playing the role of sacrificial anode. In the case of using glue, this is chosen to be conductive. Indeed the additional plate is in electrical contact with the cheek or the plates of the heat exchanger, either by direct contact with one of the cheeks or the bundle of plates, or by indirect contact via an intermediate conductive element such as glue or a mounting plate.

[0011] It should be noted that the plates of the plate bundle, the cheek and the additional plate are metallic in the sense that they comprise a majority of metal and are conductive. They can indeed contain, for example, a very thin portion of semiconductors.

[0012] According to an advantageous characteristic of the invention, the thickness of the additional plate is at least 0.5 millimeters, preferably between 0.5 and 3 millimeters, more preferably 1 millimeter. This thickness is adapted for example to the country for which the heat exchanger is intended, and to the dimensions thereof, in particular as a function of the thicknesses of the plates and of the cheek of the heat exchanger.

[0013] In one embodiment of the invention, the additional plate is brazed or welded to the cheek or to the bundle of plates. This brazing can thus be done during the brazing of the heat exchanger plates and the cheek not yet brazed, which avoids an additional operation for the assembly of this additional plate.

[0014] Preferably, the additional plate comprises a contact surface with the cheek, the contact surface representing at least 60% of an external surface of the cheek.

[0015] In this embodiment of the invention, the cheek comprises fluid connections intended to be connected to an external thermal management system, and the additional plate covers a flat surface of the cheek between the connections. fluidics. Thus the additional plate uses an unused surface of the heat exchanger, in particular not usable to compact a cooling system including the heat exchanger.

[0016] When the heat exchanger comprises a metal mounting plate secured to the cheek and comprising a portion extending beyond the bundle of plates, the portion comprising means for fixing the heat exchanger, the additional plate is for example in contact with the metal mounting plate.

[0017] In an alternative embodiment of the invention, the additional plate is itself a mounting plate for the heat exchanger comprising a portion extending beyond the bundle of plates, the portion comprising means for fixing the heat exchanger. This mounting plate is often dependent on a specific integration in a given vehicle and can therefore be specific to a given climate.

[0018] In another alternative embodiment of the invention, in which the plate bundle comprises an end plate opposite the cheek relative to the plate bundle, the cheek comprising fluid connections, the additional plate is in contact with at least 90% of a flat portion of the end plate. The additional plate can thus extend over a larger surface area of ​​the heat exchanger, up to 100% of the flat portion of the end plate.

[0019] Advantageously, the additional plate comprises indexing means capable of positioning the additional plate relative to the cheek or the bundle of plates. These indexing means are, for example, pins used to position the additional plate on the cheek or the bundle of plates before brazing the heat exchanger according to the invention.

[0020] In one embodiment of the invention, the cheek comprises fluid connections and the at least one additional plate is a first additional plate in electrical contact with the cheek, the heat exchanger comprising a second additional plate in electrical contact with an end plate of the plate bundle opposite the cheek relative to the plate bundle. This redundancy of the additional plates makes it possible to reinforce the corrosion resistance of the heat exchanger and to be less limited by the dimensions of the cheek or the plates.

[0021] Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given for informational and non-limiting purposes with reference to the appended schematic drawings on the other hand, in which:

[0022] [Fig-1] represents in perspective a heat exchanger according to the invention, and in particular a cheek of this heat exchanger equipped with fluid connections, in a first embodiment of the invention,

[0023] [Fig.2] represents in perspective the heat exchanger of [Fig.l], so as to make visible an end plate of a bundle of plates of the heat exchanger, this end plate being opposite the cheek with respect to the bundle of plates, and

[0024] [Fig.3] schematically represents in exploded perspective a heat exchanger according to the invention, in a second embodiment of the invention.

[0025] According to a first embodiment of the invention, a heat exchanger 2 according to the invention comprises a bundle of plates 4 formed of metal plates brazed or welded together. They are for example composed of an alloy of aluminum and other metals or semiconductors such as zinc, copper, silicon, etc.

[0026] Each plate extends in length in a longitudinal direction L and in width in a direction H orthogonal to the longitudinal direction L. The plates are stacked on top of each other in a transverse direction T, the dimension of this stack corresponding to the thickness or smallest dimension of the bundle of plates 4. Of course, in this application, the characteristics of the heat exchanger according to the invention follow the directions indicated to the nearest manufacturing tolerances. For example, the plates are rectangular and flat except at their edges which are curved, to the nearest manufacturing tolerances.

[0027] In a known manner, these plates form, through openings in the plates, a heat transfer liquid inlet manifold and a heat transfer liquid outlet manifold, as well as a refrigerant fluid inlet manifold and a refrigerant fluid outlet manifold.

[0028] In this first embodiment of the invention, the heat exchanger 2 comprises a cheek 6 bordering the bundle of plates 4 and allowing access to the heat transfer liquid inlet manifold and to the heat transfer liquid outlet manifold via respective pipes 8 and 10. The cheek 6 is also metallic, composed for example of an alloy of aluminum and other metals or semiconductors such as zinc, copper, silicon, etc. The cheek 6 is brazed or welded to a larger face of the bundle of plates 4. The pipes 8 and 10 are also metallic and brazed or welded to the cheek 6.

[0029] The cheek 6 also comprises a connection block 12 comprising access ports to the refrigerant fluid inlet and outlet manifolds. This connection block 12 is also metallic and brazed or welded to the cheek 6. As a variant, the access ports to the manifolds of the plate bundle 4 are not all arranged on the same face thereof.

[0030] In this first embodiment of the invention, the heat exchanger 2 comprises a mounting plate 14 brazed or welded to the cheek 6 on a first portion of this mounting plate 14. This first portion is flat, and extends over the major part of the cheek 6, in particular on the one hand between the pipes 8, 10 and the connection block 12 and on the other hand between the pipes 8 and 10. This first portion is therefore in contact with the surface of the cheek 6 opposite the bundle of plates 4.

[0031] The mounting plate 14 has an overall right-angled shape, a second portion of the mounting plate being orthogonal to the first portion and extending in the transverse and longitudinal directions, opposite the thickness of the plate bundle 4 and beyond. Fixing means 18, here a hole intended to receive a screw, are located on this second portion at a part of it projecting longitudinally from the plate bundle, and make it possible to fix the heat exchanger in a cooling system of a vehicle.

[0032] The mounting plate 14 has, for example, the same composition as the cheek 6 and is at least 0.5 millimeters thick, preferably between 0.5 and 3 millimeters, even more preferably 1 millimeter.

[0033] A first additional plate 16 of at least 0.5 millimeters thickness, preferably between 0.5 and 3 millimeters thickness, is also brazed or welded to the mounting plate 14, on a flat part of the mounting plate 14 brazed with the cheek 6, therefore gripped between the first additional plate 16 and the cheek 6. More precisely, the first additional plate 16 covers the majority of the mounting plate 14, therefore of the flat surface of the cheek 6, between the tubes 8, 10 on the one hand and the connection block 12 on the other hand. The thickness of the first additional plate 16 is for example chosen as a function of the dimensions of the cheek 6, of the bundle of plates 4 and of the mounting plate 14.

[0034] This first additional plate 16 comprises Zinc in a proportion of between 0.5 and 1.8% of its mass. The other components of this first additional plate 16 are, for example, other metals or semiconductors such as aluminum, silicon, etc.

[0035] Thus the first additional plate 16 is in electrical contact with the cheek 6 and the bundle of plates 4 and can serve as a sacrificial anode, its electrochemical potential being lower than that of aluminum, and therefore protects the cheek 6 and the bundle of plates 4 against corrosion.

[0036] Alternatively, the mounting plate 14 also comprises Zinc in a proportion of between 0.5 and 1.8% of its mass and also serves as a sacrificial anode. In another alternative, the heat exchanger 2 does not comprise the first additional plate 16 but only the mounting plate 14 serving as a sacrificial anode.

[0037] In this first embodiment of the invention, the heat exchanger 2 comprises a second additional plate 22 brazed or welded to an end plate 20 of the bundle of plates 4, opposite the cheek 6 relative to the bundle of plates 4. More precisely, the second additional plate 22 is brazed or welded to a surface of the end plate 20 opposite the other plates of the plate bundle 4.

[0038] This second additional plate 22 comprises Zinc in a proportion of between 0.5 and 1.8% of its mass. The other components of this second additional plate 22 are, for example, other metals or semiconductors such as aluminum, silicon, etc. The thickness of the additional plate 22 is at least 0.5 millimeters, preferably between 0.5 and 3 millimeters, depending on the thickness of the plates of the plate bundle 4 in particular. The additional plate 22 is here in contact with the entire flat part of the end plate 20. Alternatively, the additional plate does not cover this entire flat part but is thicker.

[0039] This second additional plate 22 also serves as a sacrificial anode against corrosion of the plate bundle 4. As a variant, the heat exchanger 2 does not include this second additional plate 22, the first additional plate 16 being sized to be sufficient to protect the entire cheek 6 and the plate bundle 4 against corrosion.

[0040] According to a second embodiment shown [Fig. 3], a heat exchanger 30 according to the invention comprises, as in the first embodiment of the invention, the bundle of plates 4 and the cheek 6 bordering the bundle of plates 4. Only a few plates of the bundle of plates 4 are shown for greater visibility. The bundle of plates 4 also comprises the end plate 20 opposite the cheek 6.

[0041] Unlike the first embodiment of the invention, in this second embodiment of the invention, the heat exchanger 30 does not include a mounting plate. In addition, the cheek 6 includes indexing pins capable of being inserted into holes 172 of an additional plate 17 brazed or welded to the cheek 6, on a surface thereof opposite the plate bundle 4. These pins and these holes 172 therefore make it possible to position the additional plate 17 during its brazing or welding to the cheek 6. Alternatively, the cheek includes indexing cavities receiving indexing pins arranged on the additional plate 17.

[0042] In this second embodiment of the invention, the additional plate 17 covers the majority of the flat surface of the cheek 6 between the tubes 8, 10 on the one hand and the connection block 12 on the other hand. The thickness of the additional plate 17 is at least 0.5 millimeters, preferably between 0.5 and three millimeters thick, the cheek 6 being one millimeter thick, the end plate 20 1.5 millimeters thick and the intermediate plates 0.35 millimeters thick.

[0043] This additional plate 17 comprises Zinc in a proportion of between 0.5 and 1.8% of its mass. The other components of additional plate 17 are for example example of other metals or semiconductors such as aluminum, silicon, etc.

[0044] Thus the additional plate 17 is in electrical contact with the cheek 6 and the bundle of plates 4 and can serve as a sacrificial anode, its electrochemical potential being lower than that of aluminum, and therefore protects the cheek 6 and the bundle of plates 4 against corrosion.

[0045] In this second embodiment of the invention, the end plate 20 also comprises an additional plate serving as a sacrificial anode, similar to the second additional plate 22 of the first embodiment of the invention. Alternatively, the heat exchanger only comprises the additional plate 17 as a sacrificial anode, the latter being sized to protect all of the plates of the plate bundle 4 and the cheek 6.

[0046] Of course, the invention is not limited to the examples which have just been described and numerous adjustments can be made to these examples without departing from the scope of the invention. In particular, the characteristics of the different embodiments or variants can be combined to achieve the invention, insofar as these embodiments or variants are not incompatible with each other.

Claims

Claims

1. Heat exchanger (2, 30) comprising a bundle of plates (4) and at least one cheek (6) bordering the bundle of plates (4), the material of the plates and of the cheek (6) comprising at least aluminum, the heat exchanger (2, 30) being characterized in that it further comprises at least one additional plate (14, 16, 17, 22) secured to the cheek (6) or to the bundle of plates (4) and forming an electrical contact with the cheek (6) or the bundle of plates (4), the additional plate (14, 16, 17, 22) comprising Zinc in a proportion of between 0.5 and 1.8% of the mass of the additional plate (14, 16, 17, 22) and in that the additional plate (14) is a mounting plate of the heat exchanger (2) comprising a portion extending beyond the bundle of plates (4), the portion comprising fixing means (18) of the heat exchanger (2).

2. Heat exchanger (2, 30) according to claim 1, wherein the thickness of the additional plate (14, 16, 17, 22) is at least 0.5 millimeters.

3. Heat exchanger (2, 30) according to claim 1 or 2, in which the additional plate (14, 17, 22) is brazed or welded to the cheek (6) or to the bundle of plates (4).

4. Heat exchanger (2, 30) according to any one of claims 1 to 3, in which the additional plate (14, 17) comprises a contact surface with the cheek (6), the contact surface representing at least 60% of an external surface of the cheek (6).

5. Heat exchanger (2, 30) according to any one of claims 1 to 4, in which the cheek (6) comprises fluid connections (8, 10, 12) intended to be connected to an external thermal management system, and in which the additional plate (14, 16, 17) covers a flat surface of the cheek between the fluid connections (8, 10, 12).

6. Heat exchanger (2) according to claim 1 or 2, in which the heat exchanger (2) comprises a metal mounting plate (14) secured to the cheek (6) and comprising a portion extending beyond the bundle of plates (4), the portion comprising means (18) for fixing the heat exchanger (2), and in which the additional plate (16) is in contact with the metal mounting plate (14).

7. Heat exchanger (2, 30) according to any one of the claims 1 to 3, wherein the plate bundle (4) comprises an end plate (20) opposite the cheek (6) with respect to the plate bundle (4), the cheek (6) comprising fluid connections (8, 10, 12), and wherein the additional plate (22) is in contact with at least 90% of a flat part of the end plate (20).

8. Heat exchanger (2, 30) according to any one of claims 1 to 7, in which the cheek (6) comprises fluid connections (8, 10, 12) and in which the at least one additional plate is a first additional plate (14, 16, 17) in electrical contact with the cheek (6), the heat exchanger (2, 30) comprising a second additional plate (22) in electrical contact with an end plate (20) of the bundle of plates (4) opposite the cheek (6) relative to the bundle of plates (4).

9. Heat exchanger (30) according to any one of claims 1 to 8, in which the additional plate (17) comprises indexing means (172) capable of positioning the additional plate (17) relative to the cheek (6) or to the bundle of plates (4).

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